Hair comes from our heads so in dreams can symbolize thoughts or how you think with regards to the subject matter of the dream.
Having your hair done or a haircut is a request to change how you think with regard to the subject matter of the dream.
Hair tied up or in a bun means your way of thinking is restricted. The restriction can be due to conditioning or it can simply be your refusal to look at things with an open mind.
Hair loss can indicate a refusal to think about something. Being bald in a dream indicates the same thing. Hair loss is also a symptom of an under active thyroid so can also indicate that.
Blonde hair indicates a guide. Whatever they say in the dream is infallible. However, if the hair is dyed blonde it indicates a sham – either you or someone in your life is pretending to be pure of thought.
Hair on fire is a threat of stroke. Look for other symbols in the dream to do with expression of feelings.